Russian President Vladimir Putin (2nd from l.) meets with members of the Holy Synod of the Ukrainian Orthodox Church of Moscow Patriarchate in Kiev, Ukraine, Saturday. Mr. Putin also met with Ukrainian President Viktor Yanukovych to urge that Ukraine join Putin's planned Eurasia customs union.

Mr. Putin used the occasion to press a far more secular and, for the Kremlin, urgent agenda. Ukraine is facing an historic choice that may determine its development for decades to come. Much of Russia's own strategic future plans also revolve around what it decides.

But Ukraine plans to sign a landmark association agreement with the European Union in November, which would grant it trade preferences with Europe and preclude membership in an alternative trading bloc such as Russia's customs union.

"This day marks the unity of our peoples. We have several common questions we will be able to discuss during these days of celebrations. There will be another meeting tomorrow… where we will talk security," the Kremlin-funded English-language RT network quoted Putin as telling Ukrainian President Viktor Yanukovych.

However, Yanukovych has been unable – or unwilling – to deliver Ukrainian agreement to join the customs union, whose main members are Russia, Belarus, and Kazakhstan, a step that might forever cement Ukraine into a Russian-led economic and political union of ex-Soviet countries. At the same time, he has insisted that Ukrainian cooperation with Europe shouldn't close the door to better relations with Moscow.

At a meeting with Ukrainian religious and political leaders Saturday, Putin made his best pitch for choosing the Russian path.

"Competition on global markets is very fierce today. I am sure that most of you realize that only by joining forces can we be competitive and stand a chance of winning in this tough environment. We have every reason too, to be confident that we should and can achieve this," Putin said, according to a Kremlin transcript of his remarks.

Putin argued that Ukraine was built up and industrialized within the USSR, and it still shares a considerable amount of common infrastructure with Russia. He claimed that living standards in Soviet Ukraine were even better than in some European countries, such as Italy.

"As you know, there are various integration processes underway now in the post-Soviet area.... There are facts that speak for themselves. Our bilateral trade with Ukraine fell by slightly over 18 percent in the first quarter of this year. Our trade with the customs union countries increased by 34 percent in 2011, by 11 percent, I think, in 2012, and was up by 2 or 3 percent in the first quarter of this year, despite the downturn in the global economy. We have steady growth," he said.

Putin added that Russia will respect Ukraine's choice, whatever it may be.

"Russia is really desperate, because Ukraine is the major trophy in Putin's Eurasian Union project. That's what leads Putin to pull out all the stops in the race to win this," says Sergei Strokan, a foreign affairs columnist with the Moscow daily Kommersant.

"Ukraine is trying to delay this choice as much as possible, because it wants to keep its European window open. But the Europeans have been quite tough, basically telling Ukraine that it can't sit on two chairs. Ukrainian public opinion is divided over this, but it seems that the dominant mood – at least of the younger part of the population – is for a European strategy. Trying to sit on two chairs is probably the best Yanukovych can do for Putin. But the European option is looming, and Ukraine will probably try to use it – regardless of what Putin wants," Mr. Strokan says.